The announcement shows that the amount purchased represents the amount of the tax liability that results from the vesting of the stock. In the USA this tax liability is due on vesting not when the tax return is lodged. So the only way they could come up with the dollars would be to sell in the open market if the company did not buy back. Not sure that you want to see an executive selling in the open market.
UNS Price at posting:
77.0¢ Sentiment: None Disclosure: Not Held